Chapter 27 Worms - Page Text Content

2: Worms are very diverse organisms. Some reproduce by fission, others sexually, and there are some which are hermaphrodite. There are three phylum that considered to form the worms category, these are: earthworms, flatworms, and round worms. Although worms seem to be simple organisms, some have brain and other organs. Worms can be either parasites or predators.

4: Flat worms are known as acoelomates and do not contain any coelom. They have a nervous system, but no brain. They can reproduce either sexually or by fission. Flatworms are divided in three classes: Flukes- (Trematoda)parasites that infect internal organs of the host; Turbellarians: (turbellaria) free living, live in fresh and marine water; and Tapeworms: (cestoda) live inside the host intestines

6: Roundworms: Phylum: Nematoda Roundworms are unsegmented worms that have pseucoeloms and have a mouth and anus. They can be either parasites or free living. They used mouth parts, such as jaws, to feed on on other organisms. Roundworms do not have internal transport and depend on diffusion. They have ganglia and a more developed nervous system useful to detect their preys.

10: Better known as "earthworms", annelids are worms with segmented bodies. The word annelid comes from the Greek annellus, meaning: "little ring". Indeed, annelids are those types of worms which appear to be covered with rings around their bodies. Annelids have a true coelom, and use pharynx to catch their pray. They do not have a heart, but have blood vessels. They reproduce sexually. Groups: oligochaetes: live in soil and fresh water. leeches: parasites that suck blood. Polychaetes: marine worms.

11: Annelids Phylum: Annelidia

12: Conclusion In conclusion, there are three phylum consider to be part of worms. These are: flatworms, roundworms, and annelids. Flatworms are the simplest type of worms. They do not have a brain and are almost flat. Roundworms are unsegmented worms, which have a mouth and an anus. They do not have internal transport, so they depend on diffusion. Finally, annelids, or earth worms are responsible for many deadly diseases around the world. This type of worms have a circulatory system and segmented bodies with rings.